GUT REACTION

Scientists have been telling us for years that if we love our gut bacteria, they'll love us back and help us with everything from easing digestion to fighting disease. Now, new research suggests that our microbiomes can even help us resist the effects of ageing... if we treat them right

- DR HELEN PILCHER

Take a stroll through the supermarket and you'll find plenty of products stuffed with 'friendly bacteria. Bacteria the good guys! Chug them down and they'll help to look after you. We're used to the idea that our guts are teeming with microbes and that they can be topped up with fancy yoghurts. We give the bacteria somewhere to live and, in return, they help us to digest our food. It's a mutually beneficial, two-way street.

Only this cosy relationship isn't quite what it seems.

Hidden among their ranks is a dark cabal of interlopers. To call them 'unfriendly bacteria' would be an understatement. These are microbial hell-raisers and as we get older, they slowly start to wreak havoc.

It turns out that our gut microbes aren't always the good guys we think they are. A growing body of evidence suggests that our gut bacteria play a key role in many of the negative aspects of ageing, such as disease, frailty and the faltering of the immune system. But all isn't lost. We may not be able to stop getting older, but as we learn to harness the power of the microbiome, we can use it to help us age better and avoid ill health.

GOOD BIOME, BAD BIOME

The gut microbiome is made up of over 100 trillion microorganisms, including various bacteria, viruses and fungi. Round them up and they would weigh about as much as a hamster. If you leave them be, though, they can be found throughout the entire length of the human gut, all the way from the mouth to the anus.

Established at birth, the gut microbiome develops through early childhood. Its makeup is a reflection of what we eat, where we live and what we do. Colonies of bacteria are laid down-some good, some bad, others somewhere in between - that then remain broadly stable for decades.